where \(\Delta _{2K\pi }^2=2m_K^2-m_\pi ^2\)  and \(M_V\)  is the mass associated with the vector nonet in the chiral and large \(N_C\)  limits.
The TFF is defined in ref. [1]} along with
the short distance constraints relating parameters of the model. Its complete expression before
imposing such constraints can be found therein.
